1. Enable pipe-lining (all platforms)
With pipe-lining enabled, your web browser will make multiple page requests simultaneously. Normally it makes only one request at a time.

In the address field type:- about:config. Hit Enter.

Look for the following entries and change their values to the provided:-

Set "network.http.pipelining" to "true"
Set "network.http.proxy.pipelining" to "true"
Set "network.http.pipelining.maxrequests" to "100".

Now right-click anywhere and go New > Integer.
Enter "nglayout.initialpaint.delay" and set the value to "0".
2. Optimise your Firefox profile with Firetune (Windows only)

Firetune is for unlocking the "many hidden speed tweaks for your computer and internet connection type. FireTune for Mozilla Firefox v1.x/v2.x was developed for an easy and fast optimization of your browsing experience with Firefox. It is based on a collection of popular and well working optimization settings used and tested by the experts. Usually you have to optimize Firefox manually, which can be time consuming and difficult for the novice user. FireTune helps you here - it includes all the performance optimizations. The only thing you must do is: make your selection. FireTune does the rest for you."

Ok, first grab MozBackup and use it to backup your profile, just in case.

Be sure to tick the "Extensions" box.

Now download and install Firetune. Now run Firetune and optimise your profile. Naturally "Fast computer / fast connection" will the best option for most people (1.5GHz+ CPU and 512MB+ RAM / broadband connection).

3. Utilise prefetching (All platforms)
Many of you maybe already doing this by running the Fasterfox extension. Uninstall that extension and install Fastererfox, the aforementioned extension with even more options.

On the "Thrash" tab tick all the checkboxes. This improvement of Fastererfox over the original Fasterfox extension lets you thwart the attempts by webmasters's at disabling Fasterfox's prefetching.

As for the "define how many number are items preloaded" radio buttons, set it to whatever you like. I've left it on the default "100".

NOTE: Many webmasters (especially those with limited bandwidth) hate Fasterfox. Prefetching can potentially eat a lot of a site's bandwidth. Whether you want to show courtesy or screw them is up to you.

On the "Fastererfox" tab, whether you tick the "Enable Enhanced Prefetching" tab is at your discretion. IMO fuck the webmasters, I want my pages to load faster.

Configuring Fastererfox will undo some of your pipelining settings from Step 1 (change the number of maxrequests). You'll have to restore this value every time after you've played around Fastererfox.

To restore this setting:-
Either A.
In the address field type:- about:config. Hit Enter.
Set "network.http.pipelining.maxrequests" to "100".

4. Run a build of Firefox optimised for your CPU and operating system (all platforms)

For Windows:-Go here. If you're running a 32-bit Windows then just grab one with the best instruction set supported by your CPU. Most CPUs of recent years should support SSE2. If you're unsure of the what instruction sets your CPU supports then download and run CPU-Z.

If you're running 64-bit Windows then grab the x64 AND x86 (32-bit) SSE2 builds. The commonly used plugins Flash and Java VM do not support 64-bit browsers (There is 64-bit Java, but fuck all is compiled with it). Run the x64 build as much as possible and use the x86 SSE2 build when neccessary (eg watching vids on Youtube).

NOTE: Don't be alarmed by the build being titled Eg "Bon Echo" or "Minefield" (etc) rather than "Mozilla Firefox". (Bon Echo is the codename of the FF 2.x branch and Minefield is that of 3.x)The Firefox name and icon are trademarked and cannot be used with non-official builds. These are non-official builds, so they cannot have the official branding. Pretty straight-forward. Please don’t ask me to build versions with the official branding.

6. (Windows only) Increase the number of half-open connections
Since Windows XP SP2, the number of simultaneous outgoing connections you've been allowed has been limited to 10. This was to help stop the spread of worms to others once you've been infected. This comes at a price, in particular your P2P performance is severely crippled.

Alternatively you could use XP-antispy. Again set the value to between 50-100.
If you're using WinXP x64 SP2 or Win2003 x64 SP2:-
You may have to boot into safe mode for this part.Download and install this modified "tcpip.sys" into your windows\system\drivers directory. Beforehand rename the existing "tcpip.sys" to something like "tcpip.sys.bak", just in case.

Reboot after applying any patch or utilising a hacked system file.

For Vista (both x86 and x64 flavours):-
Reportedly XPantispy does the job here too, just make sure you're running the latest version from the official site. (source)

I used to run Fasterfox with Pipelining but found it caused some pages not to load properly. At work in particular graphics would literally merge into each other, it caused web sites to fall to bits. I should probably give it another go.

I used to Prefetch too but not the Optimal setting, the one just below. Play fair I say. I didn't notice any increase in speed mind you.

Thanks Eva. FF and Pages definitely seem to load much quicker. The "nglayout.initialpaint.delay" option I'd guess has a lot to do with this.

I opted not to enable Prefetching but fair enough if you want to use it. IMO it's overkill to cache every link on a site just because you "may" click on it. I also decreased the FastBack rendering option from the default 5 to 3, 5 is overkill IMO and just eats RAM.

FYI if you choose Turbo Charged in Fastererfox and then choose Custom it will actually leave the settings set to whatever Template (such as Turbo Charged) you had previously meaning you can then alter maxrequests without losing it when you tinker with Fastererfox.

Aren't 100 Maxrequests overkill btw? Even Turbo Charged sets it to 8.

What does FireTune do btw? The software doesn't tell you much. I also ticked "Optimise Firefox memory usage", again no idea what it really does. It can't do much as FF still uses 50MB+.

p.s - The options you talk about in number 1 are covered by Fasterfox, are they not?

Windows Vista now require all kernel-mode driver or software to be signed with digital signature in 64-bit Vista, and all boot-start drivers must be embedded-sign with signature on both x86 and x64 versions of Windows Vista. Unfortunately, tcpip.sys is both kernel mode driver, and also boot start driver, and modify tcpip.sys will break the existing signature, making the patched tcpip.sys unsigned.

So when using patched tcpip.sys, users must press F8 at every Windows boot load. When come to Vista Advanced Boot Options menu, select “Disable Driver Signature Enforcement” to bypass driver signing check and continue loading Windows Vista, else there may be boot-failure.

They're all the same info but just in case one link goes dead here are a few. ReadyDrive Plus looks to alter the Bootloader so "Driver Signature Enforcement" is Disabled (instead of Enabled) by Default.